Question: Find the greatest common factor of $7$ and $7$.
Solution: The greatest common factor (GCF) is the largest number that is a factor of $7$ and $7$. Since $7$ is a prime number, we cannot factor it any further. Also, since $7=7$, they share $7$ as their one prime factor. So the GCF is $7$. The greatest common factor of $7$ and $7$ is $7$. In general, the greatest common factor of any number and itself is that number.